Experiment And Application Of Earth-to-Air Heat Exchanger System

The Earth-to-Air Heat Exchanger(EAHE)system is an effective energy saving technique for heating and air conditioning by shallow soil energy,which has been applied in residential and public buildings now,but a lot of experimental research still needed because of other factors it may involved.In this paper,the influence factors of soil air heat exchange system are deeply explored by consistent of theoretical analysis,scale model experiment and numerical simulation.On this basis,a preliminary design scheme for the EAHE system of Yan’an revolutionary literature museum is proposed.By the dimensionless analysis of the differential equation of momentum and the differential equation of heat conduction,respectively,the key criteria for the EAHE system,namely,Reynolds number Re and Fourier number Fo,are proposed.On the basis of this,a test rig was built to satisfy all the parameters.The influence of tube length,pipe diameter,buried depth of pipeline and inlet air velocity on heat transfer performance of EAHE system is studied by using the experimental table.The results show that the heat transfer effect increases with the increase of pipe length,and decreases with the increase of the pipe diameter and inlet air velocity.Although the effect of heat transfer increases with the increase of the buried depth of the pipe,but the effect of the depth of the pipe on the heat transfer capacity is not that obvious after the 4 meter.In practical application,the depth of the pipeline is about 4m from the aspects of economic and construction practicability.On the basis of processing the experimental data,the fitting formula of tube length,pipe diameter,buried depth of pipeline and inlet air velocity and outlet air temperature can be obtained.On the basis of theoretical analysis and experimental research,the feasibility of the application of EAHE system in Yan’an area is analyzed,which conclude that it is viable Yan’an area.Combined with the practice of Yan’an revolutionary literature and art memorial hall,the preliminary design scheme of EAHE system are proposed,and it is demonstrated by numerical simulation.The results show that in summer,the system can meet the requirements of indoor temperature,but when it comes to winter,because of the low outdoor temperature,the individual EAHE system is not capable support the temperature requirement,which needs to be used in combination with other systems.